The team crossed individuals of branching coral Acropora millepora from the far northern Great Barrier Reef with members of the same species at Orpheus Island, 540 km further south. They found that corals living in warmer waters on the north of the Great Barrier Reef pass on higher temperature tolerance to their offspring.

The study also suggests that ‘Mum is best’: coral larvae had up to a ten-fold increase in their chances of surviving heat stress, of which five-fold was contributed by the mother. A possible explanation was provided by genetic analysis: tolerant larvae had altered expression of genes working in mitochondria, the powerhouses of the cells that are inherited solely from mothers.

“This discovery adds to our understanding of the potential for coral on the Great Barrier Reef to cope with hotter oceans,” says Dr Line Bay, an evolutionary ecologist from AIMS in Townsville and joint senior author on the paper.

“Averting coral extinction can begin with something as simple as exchange of coral immigrants across latitudes, which will happen naturally through larval dispersal but can be jump-started by humans moving adult corals,” says Mikhail Matz, a professor of integrative biology at the University of Texas at Austin and co-lead author. “This is occasion for hope and optimism about coral reefs and the marine life that thrive there.”

Reefs around the world are threatened by climate change. A new study shows that some corals have the genes to adapt to warmer oceans. Photo: Ray Berkelmans, AIMS

Identifying reefs with heat-tolerant coral communities and protecting them so that they naturally repopulate other reefs

Before such steps are considered we need to learn much more about coral adaptability to be able to discriminate between ‘winners’ and ‘losers’ in the game of climate change. One of the first tasks would be to confirm the role of mitochondria in heat tolerance, which was suggested for the first time by this study.